Magnetic recording materials such as lithographic printing plates, various optical films, silver halide films, photographic papers and base films of videotapes are manufactured by applying and drying a coating liquid, such as a photosensitive layer forming liquid or thermosensitive layer forming liquid, a photosensitive emulsion or a magnetic layer forming liquid, on a beltlike body such as a supporter web, a base film or a baryta paper, while the beltlike body is made to travel in a certain direction, and thereafter, by cutting the beltlike body into a predetermined size as required.
In such a process, drying and removing precisely a solvent contained in the coating liquid is said to be preferable in view of quality of products.
Conventional drying techniques generally involve methods using dry hot air. Besides, various drying methods using hot air containing a solvent vapor are proposed.
For example, Patent Document 1 proposes an apparatus for continuously drying an object containing moisture by using superheated steam. Patent Document 2 proposes an apparatus to dry and process food by using superheated steam.
Patent Documents 3 and 4 propose vapor driers to precisely remove water droplets and other contaminants from device parts by using a combustible solvent vapor such as isopropyl alcohol or an equivalent low-firing point solvent.
Patent Document 5 describes a method proposed using a theoretical analysis by Vrentas et al. as a removing method of a residual solvent in a coated film (J. Appl. Polym. Sci., 30, 4499 (1985)). Vrentas et al. cite that factors making it difficult to remove a high-boiling point solvent and the like remaining in a polymeric resin involve that the diffusion coefficient of the solvent in the polymeric resin sharply decreases as the amount of the solvent remaining in the polymeric resin decreases and that the diffusion coefficient of the solvent in the polymeric resin becomes smaller as a size (molecular volume) of the solvent molecule itself becomes larger. Hence, Vrentas et al. propose, for a polymeric resin film in which a trace amount of a high-boiling point solvent remains: 1) to expose the film to a solvent vapor having a smaller molecular volume than the high-boiling point solvent and heat it; and 2) to take out the film from a second solvent vapor atmosphere and heat it.
Patent Document 1: Japanese National Publication of International Patent Application No. 9-502252
Patent Document 2: Japanese Patent Application Laid-Open No. 2002-333275
Patent Document 3: Japanese National Publication of International Patent Application No. 2000-516334
Patent Document 4: Japanese Patent Application Laid-Open No. 2002-367950
Patent Document 5: Japanese Patent Application Laid-Open No. 2000-158814